Today, the development of low-power, long-endurance Unattended Ground Sensor (UGS) technologies is critical in supporting persistent sensing missions for military and homeland security related operations. However, the successful large-scale deployment of UGS systems for these applications will only become feasible with significant technical advancements in key areas related to sensing performance, power consumption and communications. Below I address these issues as they relate to current UGS technologies.
To reduce the workload on users and improve the operational utility of sensing missions, UGS systems are required to achieve very high probabilities of detection (Pd) and low probabilities of false alarms (Pfa) against human and vehicle targets in very difficult sensing environments. These environments include foliage, urban, and mountainous terrain. Conventional UGS technologies that leverage acoustic and seismic approaches to sensing are plagued with high false alarm rates, poor classification performance, small detection ranges and an inability to generate high quality target information, such as head count, position localization, or tracks.
Sensor systems deployed in remote regions will have no access to electrical power sources; therefore, new advancements in power management for UGS are critical to achieving the required operational endurance that is needed to meet user needs. These advancements include the ability to: (1) perform precision power cycling of electronic systems; (2) scavenge and effectively store available energy from the environment; and (3) significantly reduce system power consumption requirements through novel Application Specific Integrated Circuit (ASIC) design approaches.
Low-latency, robust communication of target information from the sensor to the analyst is critical for providing actionable intelligence and, thus, an effective response to target activities. Robust UGS communications and networking have proven to be a significant challenge because of a host of issues associated with near-ground communications where propagation losses are significant and variations in terrain elevation can result in the loss of node-to-node communication links. Because most sensor network architectures are ad hoc, directional antennas are impractical and, thus, achieving and maintaining reasonable communications links require significant transmit power. These key communication issues significantly limit node-to-node spacing, reduce node-to-node data rates, increase power consumption and complicate node deployment scenarios as ensuring adequate node-to-node spacing in highly variable propagation environments becomes difficult with both airborne and hand-emplacement scenarios.
Moreover, distributed, multi-hop sensor network architectures that are used in most networked UGS systems collect information at the node-level and relay it through the network to an external relay device for exfiltration. This network and relay architecture is inherently latent as the flow of information from node-to-node through the is network is dependent on the transmit and receive schedule implemented within the Media Access Control (MAC) protocols. With UGS networks comprising large numbers of nodes with highly constrained power consumption requirements, network latencies can grow to significant time scales.
Achieving the persistent sensing needs of military and homeland security missions requires significant advancements in sensing performance, operational endurance and communications reliability over today's UGS technologies. Below, we describe a next generation UGS technology, termed High Performance (HiPer) UGS, whose design provides a promising new approach to ground sensing and, thus, meets many of the challenging and critical requirements associated with military and homeland security sensing missions.